川西高原季节性雪被覆盖对窄叶鲜卑花凋落物分解和养分动态的影响

2010年1-5月在川西高原采用人工雪厚度梯度试验(0、30和100 cm),应用网袋分解法对窄叶鲜卑花叶片凋落物进行分解试验,测定了凋落物的分解速率及其养分动态.结果表明:在无雪被覆盖的样地上分解5个月后的凋落物质量损失率为29.9％,而中雪和深雪样地的凋落物质量损失率分别为33.8％和35.2％.分解过程中,凋落物氮存在一定的富集现象,磷处于波动的富集状态,碳质量分数和碳氮比均呈现前期急剧下降后期逐渐上升的趋势.雪被覆盖显著增加了凋落物的质量损失率和氮含量,而对碳和磷含量无显著影响.在川西高原地区,30 cm以上的持续雪被覆盖能够改变凋落物的分解过程,从而可能对土壤营养物质转化和植物群落构建产生实质性的影响.     

放牧干扰对青藏高原东缘窄叶鲜卑花空间结构的影响

在四川西北部松潘县卡卡沟对青藏高原东缘高海拔地区3个不同放牧强度下的窄叶鲜卑花灌丛的空间结构进行了研究,结果表明：放牧干扰对卡卡沟东南坡的窄叶鲜卑花空间结构影响显著,植株的总生物量、总叶面积和茎的边材面积在重度放牧下显著低于轻度和中度放牧梯度样地。中度和重度放牧情况下叶片长度、宽度以及面积均比轻度放牧显著提高;植株高度随放牧强度增加出现先升后降的现象,而顶部枝叶生物量分配则出现与之相反的情况。虽然植物空间结构发生变化,但是单位边材面积上支持的叶面积并没有变化,中度放牧使植株枝叶生物量更加均匀分布。放牧干扰下植物空间结构的塑性变化依然受到Huber数的制约,使叶片蒸腾耗水与茎的供水能力上维持平衡。     

COORDINATNE NUCLEAR AND CHLOROPLAST DIVISION IN UNILOCULAR SPORANGIA OF LAMINARIA ANGUSTATA (LAMINARIALES,PHAEOPHYCEAE)1

Changes in the number of nuclei and chloroplasts were examined during the process of unispore formation in unilocular sporangia of Laminaria angustata. Just before meiosis, eight chloroplasts were always present in unilocular sporangial mother cells. The number of chloroplasts remained constant through meiosis. After the resulting four nuclei divided again (third nuclear division), a close association between a nucleus and a chloroplast developed among each of the eight nuclei and eight chloroplasts. The eight chloroplasts divided ahost synchronously before the synchronous division of the eight nuclei. Following the 16 nucleate stage with 16 chloroplasts and the final 32 nucleate stage with 32 chloroplasts, 32 unispores, each with a nucleus and a chloroplast, were fomd in unilocular sporangza of L. angustata. Immunofluorescence microscopy using an anti-centrin antibody showed that two anticentrin-stained structures (as future mitotic poles) occurred adjacent to each of the premitotic four nuclei, and each spot was located near a chloroplast. Therefore, after the third division, each of the eight nuclei established close contact with a chloroplast presumably mediated by the centrosomes.     

Stoichiometric characteristics of carbon,nitrogen and phosphorus of Sibiraea angustata shrub on the eastern Qinghai-Xizang Plateau

Aims Little is known about the stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) in plateau shrubs across China. Sibiraea angustata is a typical and representative shrub species on the eastern Qinghai- Xizang Plateau, and exploring its C, N and P distribution patterns and stoichiometric properties in different organs (including root, shoot, leaf, twig and fruit) would help us better understand the mechanisms of C, N and P cycling and balance in the S. angustata dominated shrub ecosystem.
Methods Sixteen sampling sites were selected on the eastern Qinghai-Xizang Plateau by the stratified sampling method. The height and coverage of the dominant shrubs, latitude, longitude and altitude of the sites were recorded. Three 5 m × 5 m plots were selected at each site. At least 128 biological samples of plant organs of S. angustata were collected and measured, respectively. The C and N concentrations of plant samples were analyzed using an elemental analyzer (2400 II CHNS). The P concentration was analyzed using the molydate/ascorbic acid method after H₂SO₄-H₂O₂ digestion.
Important findings The C, N and P concentrations of different organs followed the order of: shoot (495.07 g·kg^-1) > twig (483.37 g·kg^-1) > fruit (480.35 g·kg^-1) > root (468.47 g·kg^-1) > leaf (466.33 g·kg^-1); leaf (22.27 g·kg^-1) > fruit (19.74 g·kg^-1) > twig (7.98 g·kg^-1) > shoot (4.54 g·kg^-1) > root (4.00 g·kg^-1) and fruit (2.85 g·kg^-1) > leaf (1.92 g·kg^-1) > twig (0.96 g·kg^-1) > root (0.52 g·kg^-1) > shoot (0.45 g·kg^-1), respectively. The ranges of the coefficient of variation (CV) for C, N and P concentrations were 1.71%-4.44%, 14.49%-25.50% and 11.46%-46.15%, respectively. Specifically, the C concentration was relatively high and stable, and the maximum CV values for N and P were found in roots. The N:P value of different organs varied from 7.12-12.41 and the minimum CV for N:P was found in twig, which indicated that N:P in twig had higher internal stability. In addition, correlation analysis indicated that the C concentration was significantly negatively correlated with N and P concentrations and correlation coefficients were -0.407 and -0.342, respectively. However, N concentration had dramatically positive correlation with P concentration and the correlation coefficient was 0.814. These results also could indicate that the C, N and P stoichiometric characteristics in the S. angustata shrub accorded with the homeostatic mechanism and growth rate hypothesis to some extent, the distributions of C, N and P concentrations were closely related to the function of the organs and it should be prudent to use ecological stoichiometric ratios to judge the condition of nutrient limitation at the species level.     

Guluronate content of alginate in Laminaria japonica and Laminaria angustata fronds in laboratory culture

The guluronate (G) content of alginate in the fronds of Laminaria japonica and Laminaria angustata, cultured in the laboratory from zoospore via gametophyte using PESI medium, was determined by the ¹H‐nuclear magnetic resonance spectroscopic method. The G content of alginates in young fronds cultured in various conditions were shown to exceed 55%. These values were remarkably higher than those in field kelp. The G content increased with extending culture period and at low temperature.     

IMMUNOFLUORESCENCE MICROSCOPY OF FERTILIZATION AND PARTHENOGENESIS IN LAMINARIA ANGUSTATA (PHAEOPHYTA)1

Normal fertilization and parthenogenesis of unfertilized eggs were observed in Laminaria angustata Kjellman by indirect immunofluorescence microscopy using a tubulin antibody. Sperm aster formation did not occur at plasmogamy. The centrosome of the egg gradually disappeared. Shortly after karyogamy, one centrosome reappeared near the zygote nucleus. During mitosis, the centrosome replicated and the daughter centrosomes migrated to opposite poles. The mitotic spindle was formed by microtubules that elongated from both poles. After the first cell division, each of the daughter cells received one centrosome that persisted throughout the development of the sporophyte. During parthenogenetic development, abnormal mono-, tri-, and multi-polar spindles were formed. These abnormal spindles caused abnormal nuclear and cytoplasmic division. Thus, cells were produced with 1) no nuclei, 2) multiple nuclei, 3) irregular numbers of chromosomes, and/or 4) no centrosomes. This is one of the reasons for the abortion and abnormal morphogenesis during parthenogenesis. Ultrastructural observations showed that, although cells of some parthogenetic sporophytes have centrioles, cells of almost all abnormally shaped parthenogenetic sporophytes lack centrioles. These results suggest that centrioles are required for normal centrosomal functions in Laminaria. Although centrioles are inherited paternally, some centrosomal material appears to be present or produced de novo in unfertilized eggs.     

莴苣叶疫病和茎腐病的病原

2021年3-6月,从甘肃省的生菜(叶用莴苣)叶片和青海省的莴笋(茎用莴苣)茎秆罹病样本上分离得到腐霉属卵菌。通过Koch’s法则明确了分出菌株的致病性。依据形态学和分子生物学特征,将3个菌株鉴定为嗜导管腐霉Pythium tracheiphilum。在核糖体DNA内转录间隔区(rDNA-ITS)、细胞色素氧化酶亚基1 (cox 1)和核糖体DNA 28S大亚基(rDNA-LSU)基因联合系统发育树中,甘肃菌株(LPy-B)和青海菌株(LPy-C和LPy-D)被聚在P. tracheiphilum的不同亚群里,不同菌株的适宜生长温度和产孢特性存在差异。孢子囊顶生、间生或侧生,球形,17.13-53.73 μm,或近球形至葫芦状,24.58-56.72×18.62-53.73 μm;休止孢球形,6.70-9.68 μm;藏卵器光滑,顶生或间生,球形,15.64-23.09 μm;每个藏卵器有雄器1-2个,雄器与藏卵器同丝或异丝生;卵孢子满器或近满器,球形,直径13.41-20.11 μm,卵孢子壁厚0.74-2.23 μm。致病性测定结果表明,除莴苣外,嗜导管腐霉还可侵染菊科的华蒲公英和刺儿菜、十字花科的青菜、豆科的蚕豆;不侵染车前科的车前、马齿苋科的马齿苋和苋科的反枝苋;在试验条件下,菌株LPy-C和LPy-D对青菜叶片的致病性强于LPy-B。嗜导管腐霉及其引起的莴苣叶疫和茎腐病在我国和亚洲地区系首次报道。     

蒙古香蒲,宽叶香蒲和长苞香蒲花粉的黄酮类化合物的研究

蒙古香蒲(Typha davidiana Hand.-Mazz.)宽叶香蒲(Typha latifolia L.)和长苞香蒲(Typha angustata Bory et Chaub)的干燥花粉中分别分离得到柚皮素(Ⅰ),异鼠李素(Ⅱ),檞皮素(Ⅲ),异鼠李素-3-O-(2~G-α-L-鼠李糖基)-芸香糖甙(Ⅳ),檞皮素-3-O-(2~G-α-L-鼠李糖基)-芸香糖甙(Ⅴ),异鼠李素-3-O-芸香糖甙(Ⅵ),异鼠李素-3-O-新橙皮糖甙(Ⅶ)和山奈酚-3-O-新橙皮糖甙(Ⅷ)。     

To which genus of Asteraceae does Liabum oblanceolatum belong? Vegetative characters have the answer

The West Indian species Liabum oblanceolatum Urb. & Ekman was established on the basis of sterile young specimens represented by acaulescent herbs with rosulate leaves. However, these specimens have important traits that do not correspond to Liabum Adans. More than 90 genera of Asteraceae occur in Hispaniola (= Santo Domingo), but only 14 of them include species represented by acaulescent herbs with rosulate or grouped leaves at the base of the stem. From these genera, Chaptalia Vent. and Liabum are the most similar to the types of L. oblanceolatum . Habit, leaf arrangement, lamina shape, leaf margin, leaf surface, leaf margin intrasection, leaf venation, leaf pubescence, leaf trichomes, stomata and upper surface leaf cuticle were analysed in the type specimens of L. oblanceolatum and in species of Chaptalia and Liabum of Hispaniola. The vegetative trichomes are described in detail. The analysis reveals that the type specimens of L. oblanceolatum fit with all the vegetative traits of Chaptalia angustata Urb. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 479–486.     

窄叶鲜卑花(Sibiraea angustata)nrDNA ITS和cpDNA trnL-F序列分子进化特点的分析

应用PCR产物直接测序法分析了窄叶鲜卑花居群间nrDNA(核糖体DNA)ITS序列和cpDNA(叶绿体DNA)trnL-F的碱基差异,并与cpDNAtrnS-G序列和rpl20-rps12序列进行比较,从而初步研究两套植物基因组的变异速率。采用改良的CTAB法从硅胶干燥的窄叶鲜卑花叶片中提取总DNA,并对nrDNA ITS和cpDNAtrnL-F区域进行扩增、纯化、测序。nrDNA ITS序列共有601 bp,有变异位点3处,变异位点百分率为0.05%,(G+C)含量为41.4%。cpDNAtrnL-F序列共有927 bp,有变异位点1处,变异位点百分率0.01%,(G+C)含量为32.6%,两种序列的核苷酸多样性非常低。比较发现,窄叶鲜卑花nrDNA ITS区域较cpDNAtrnS-G序列和rpl20-rps12序列保守,变异速率较慢,比cpDNAtrnL-F序列变异速率稍快。通过对ITS序列单倍型(haplotype)进行分析发现,窄叶鲜卑花现有分布范围经历了居群近期范围扩张,与叶绿体基因组(trnS-G和rpl20-rps12序列)得出的结论一致。因此,窄叶鲜卑花nrDNA ITS序列适合该种的谱系地理学研究。